Neutron detector developments at LPC Caen  -delayed neutron detectors  current limitations  future issues Search for new solid scintillators (Neutromania) Simulations for future neutron arrays Developments of digital electronics

TONNERRE EXOGAM TONNERRE array 32 bars, 160 x 20 x 4 cm 3 BC400 plastic Up to 45% of 4  Intrinsic  n ~ 45% at 1 MeV E n from TOF (d=1.2 m)  E n /E n ~ 10% Threshold : E n ~ 300 keV  -delayed n detectors : current state of the art A. Buta et al., NIM A455 (2000) 412

 n detectors : current limitations time-of-flight (ns) number of counts 46 Cl 29 S. Grévy and the TONNERRE collaboration No n-  discrimination :  background  E n /E n limited by thickness & d flight Tails : slow scintillation component? light transmission?

 2n with current detectors Test on 11 Li(  ) 9 Be+2n with TONNERRE (F.M. Marqués et al.)  n  +  +  2n background dominant n-  discrimination needed

n-  discrimination : background reduction, multiple neutrons (eg  2n)  liquid scintillators or new solid scintillators improve E n resolution  increase distance of flight, thin detectors cross-talk rejection : multiple neutrons (eg  2n)  modular, high granularity lower threshold :  thin, small volume detectors, digital electronics, good discrimination Issues for future  -delayed neutron detectors From  -n Meeting, LPC, Feb & Neutron Detector Workshop, Madrid, July 2006

Possible test experiment in 2008 : feasibility of  2n with n-  discrimination learn about issues  EDEN (NE213, 5 cm thick) and standard electronics test of digital electronics (LPC or other)  xn detectors : plans

Neutromania at Caen Sample synthesis at LCMT-ENSICAEN (chemistry lab) : PMMA- or polystyrene-based polymers various fluors tested secondary solvents and/or solutes (naphthalene, POPOP…) Scintillation and discrimination properties tested at LPC with sources Results : no major difficulties to obtain scintillation  some samples show high light output (~BC400) discrimination is challenging  no sample shows discrimination Understand discrimination mechanisms : test of current solid & liquid scintillators T. Dalet et al., in preparation

Discriminating plastic Qslow Qtotal Test at LPC with digital ADC : 2 GHz, 12 bits, 2500 samples (1.25  s), low rate « plastic 77 », Brooks et al, IRE Trans. Nucl. Sci., NS-7, 35 (1960) No exotic compounds (similarities with NE213) Light output ~ BC400 Clean synthesis process (CEA Saclay) neutrons  

Geant4 simulations Design future neutron detectors for fast neutrons from breakup reactions (Eurisol)  -delayed neutron spectroscopy (Spiral2, Eurisol)  2 year postdoc (Eurisol DS, task 10), Brian Roeder Why Geant4 ? handles complex geometries tracking built-in lots of available physics models for particle interactions But need to validate

Geant4 issues B. Roeder } built-in elastic & inelastic models } inelastic cross-sections from Menate No satisfying models

Geant4 simulations with home-made model Develop our own models  Start with low energy elastic scattering on H & C  Data-based model Good at low energy Add inelastic scattering… B. Roeder

Geant4 simulations with home-made model Home made Looks good Add inelastic scattering… B. Roeder

Digital electronics developments Planned developments : Digital CFD Digital trigger Neutron-detector dedicated electronics ADCFPGA TOF Qslow Qfast CFD, gates... Issues for n-detector electronics : What ADC sampling rate do we need for timing ~500 ps? What resolution for Qslow/Qfast? Improve n-  discrimination? PhD starting Nov D. Etasse et al Detector Current developments : Fast DAQ, « FASTER » Digital Spectroscopy Amplifier

Conclusions & Outlook New materials : solids can discriminate n &  why? how? Design of future n-detectors : simulations being tested & improved special emphasis on cross-talk performances (multiple neutrons)  first designs in 2008/2009 Digital electronics : developments in the next 3 years (PhD) test experiment ~ 2008 improve n-  discrimination? Feasibility of  2n : test experiment with thin detectors & discrimination (~2008)  issues, improvements

The DEMON array Neutrons from break up tens of AMeV 96 modules, 16 x 20 cm 2 (4 liters) NE213 liquid scintillator n-  discrimination E n from TOF (d~3 m) Modular : position, solid angle, cross-talk rejection E n threshold ~ 2 MeV Intrinsic  n > 30 % for 3 < E n < 60 MeV Angular acceptance ~ 30%

DEMON & digital electronics Q slow vs Q fast 137 Cs source Q slow vs Q fast AmBe source Test at LPC with digital ADC : 2 GHz, 12 bits, 2500 samples (1.25  s), low rate

DEMON efficiency with Menate DEMON intrinsic efficiency All processes H(n,n) C(n,np) C(n,p) C(n,n’3  ) C(n,  ) MENATE simulation Neutron energy (MeV) Efficiency 500 keVee threshold Simple Reasonably accurate Only cylindrical detectors with NE213 scintillator P. Désesquelles et al, NIM A 307, 366 (1991) Reactions : H(n,n) 12C(n,n) 12C(n,n’  ) 12C(n,2n) 12C(n,  ) 12C(n,n’3  ) 12C(n,p) 12C(n,np)

n-  discrimination with digital electronics With digitized n &  signals (eg from DEMON) : discrimination with Qslow/Qfast comparison : optimal gates event by event baseline correction no signal splitting  discrimination threshold?  E n threshold?  better separation? develop & test new discrimination algorithms